The invention relates to an apparatus for producing an indication of the horsepower produced by a motor, engine or the like.
Horsepower is the unit of power commonly used to express the power developed at any given moment by a motor or engine. That power is a product of the torque developed by the engine, the speed of rotation of the engine, i.e., revolutions per unit of time, and a constant. Thus, one way to determine and indicate the horsepower of an engine or motor is to detect both the torque and speed of the engine in revolutions per unit of time and to combine these values to determine the horsepower, i.e., EQU Horsepower=Torque.times.K(A constant).times.Speed in revolutions per unit time.
One way in which this is conventionally accomplished is to detect the torque by means of an eddy current brake coupled to the motor shaft. The current produced in the brake indicates the torque. Speed is measured by coupling a tachometer to the shaft and the signals thus produced are combined to provide an indication of horsepower. Other devices have been developed which utilize strain gauges in order to ascertain the torque and magnetic pickup devices to produce a signal indicating the speed of rotation. These two electrical signals are then multiplied together and displayed to provide an indication of horsepower.
The present invention relates to an improved apparatus for indicating the horsepower produced by a motor. The torque is detected by means of a load beam or cell which measures tensile or compressive forces. Many suitable load cells are available. The D. C. signal produced by the load cell is applied to a torque circuit which provides an output pulse having a width indicating the torque, i.e., the width of the pulse varies with the detected torque. The torque circuit also includes an analog-to-digital converter operating as a dual-slope integrating device for converting the output of the load cell or beam to a digital value which can then be conventionally displayed in a seven segment LED display.
The speed of the motor is also detected, e.g., by means of a conventional magnetic sensor with the output applied to a circuit which produces a train of pulses having a frequency indicating the speed of revolution. The output of the tachometer circuit is also displayed.
The torque circuit and the tachometer circuit are connected to a horsepower circuit which includes a counter connected to the output of the tachometer circuit for counting the pulses produced by that circuit. A clock circuit in the horsepower circuit operates at a variable frequency indicating the constant K, and supplies the pulses counted by the A/D converter in the torque circuit so that the pulse width also varies as a function of the constant K. The horsepower circuit further includes a counter logic responsive to the output of the torque circuit for accumulating a count of the tachometer pulses during the duration of the pulse from the torque circuit. This count then indicates the horsepower and can be conventionally displayed.
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.